Congestive Heart Failure in Dogs: What It Is, What Causes It, and How To Treat It

A dog's heart continuously and efficiently pumps oxygen-rich blood throughout the body. Heart disease, however, makes the heart unable to function properly. When this happens, blood stops flowing well through the heart and body. Blood vessels get clogged and organs don't receive enough oxygen-rich blood.

Poor heart function ultimately leads to congestive heart failure. Congestive heart failure in dogs is not curable but can be managed to improve quality of life.

What Is Congestive Heart Failure in Dogs?

Congestive heart failure (CHF) is the end result of underlying heart disease that makes the heart unable to efficiently pump blood. In a healthy heart, blood flow is tightly orchestrated. Valves separate the heart chambers and prevent the backflow of blood.

Heart disease disrupts normal blood flow through the heart, eventually leading to CHF. CHF is left-sided or right-sided, depending on which side of the heart is affected.

Left-sided CHF occurs when blood flows backward from the left ventricle to the left atrium through the mitral valve. Blood accumulates in the left atrium and then the lungs. Eventually, the lungs' blood vessels become leaky, causing pulmonary edema (fluid-filled lung tissue).

Right-sided CHF occurs when blood flows backward from the right ventricle to the right atrium through the tricuspid valve. A blood-filled right atrium leads to clogged systemic blood vessels. Fluid then leaks into the abdomen (ascites) and causes limb swelling (peripheral edema).

What Causes Congestive Heart Failure in Dogs?

Mitral valve insufficiency and dilated cardiomyopathy (DCM) are the most common causes of canine CHF. Mitral valve insufficiency commonly affects small breed dogs and allows blood to flow backward from the left ventricle to the left atrium. DCM usually affects large breed dogs. It occurs when the heart muscles weaken and the heart cannot efficiently pump blood.

Other causes of CHF in dogs include:

• Infection
• Heartworm disease
• Nutritional deficiencies
• Tricuspid valve disease
• Congenital heart defects
• Abnormal heart rhythm (arrhythmia)

Signs and Symptoms of Congestive Heart Failure in Dogs

The signs of CHF in dogs depend on which side of the heart is affected. Remember that any signs of difficulty breathing requires emergency treatment.

Left-sided CHF symptoms:

• Collapse
• Lethargy
• Fainting
• Excessive panting
• Pale or blue gums
• Persistent coughing
• Exercise intolerance
• Rapid, difficult breathing

Right-sided CHF symptoms:

• Swollen limbs
• Reduced appetite
• Swollen belly (ascites)
• Discomfort when lying down

Diagnosis of Congestive Heart Failure in Dogs

Diagnosing CHF in dogs involves closely examining the heart and overall health and, if possible, identifying the underlying heart disease. During the physical exam, your veterinarian will listen to your dog's heart rhythm and lungs. With left-sided CHF, the lungs sound congested because of fluid buildup.

Chest X-rays are performed to look for pulmonary edema and heart enlargement. Basic laboratory testing, including blood work, will provide information about your dog's overall health and organ function.

Heart tests include the electrocardiogram (ECG) and echocardiogram. An ECG measures heart rate and rhythm. An echocardiogram is an ultrasound of the heart; it measures heart chamber size and thickness and evaluates the heart's pumping ability.

Using diagnostic test results, your veterinarian will classify the stage of your dog's heart disease, described below, to determine a treatment plan.

• Stage A: Risk of heart disease but no symptoms
• Stage B: Presence of a murmur, ± structural changes to the heart, but no symptoms
• Stage C: CHF is present and responding well to treatment
• Stage D: CHF is present and not responding to treatment

How to Treat Congestive Heart Failure in Dogs

Treating congestive heart failure depends on the type and severity of your dog's underlying heart disease and whether the CHF is left- or right-sided. CHF treatment goals are to maximize the heart's pumping ability and minimize fluid buildup.

Various medications are available to treat CHF in dogs, including:

• Diuretics: Diuretics are the mainstay of CHF treatment in dogs. They help flush excess fluid out of the system
• ACE inhibitors: ACE inhibitors make it easier for the heart to pump blood
• Positive inotropes: Positive inotropes promote heart muscle strength, improving pumping ability

Other treatment methods may be needed, including:

• Fluid removal: Severe fluid buildup may require periodic manual fluid removal from the lungs (thoracocentesis) or abdomen (abdominocentesis)
• Oxygen supplementation: Dogs with severe respiratory distress may need oxygen supplementation

A high-quality diet can improve your dog's heart health, thus improving heart function and reducing CHF symptoms. Your veterinarian can provide guidance on dietary changes, such as omega fatty acid supplementation. Follow-up appointments are needed to re-evaluate the heart and assess fluid buildup. These appointments will include chest X-rays, blood work, and an echocardiogram.

What's the Prognosis for Dogs with Congestive Heart Failure?

Unfortunately, congestive heart failure in dogs is not reversible. The prognosis depends, in part, on the underlying heart disease. For example, only about 50 percent of dogs with mitral valve disease will live beyond about 10 months.

Treatment can improve quality of life and even slightly extend life expectancy, but dogs with CHF usually do not live beyond one year of their diagnosis. Your veterinarian will be able to help come up with the best care and treatment plan for your individual dog.

How to Prevent Congestive Heart Failure in Dogs

Congestive heart failure in dogs cannot be prevented. However, early detection and treatment of heart disease, as well as good nutrition and regular exercise, can promote good heart health and minimize the risk of developing CHF.